Mass defect

Definition

Mass defect is the difference between the mass of an atomic nucleus and the sum of the masses of its individual protons and neutrons. This difference arises due to the binding energy that holds the nucleus together.

5 Must Know Facts For Your Next Test

1. The mass defect is a direct result of the nuclear binding energy, which is released when a nucleus is formed from protons and neutrons.
2. Mass defect can be calculated using Einstein's equation $E=mc^2$, where $E$ is the binding energy, $m$ is the mass defect, and $c$ is the speed of light.
3. A larger mass defect generally indicates a more stable nucleus because more energy was released during its formation.
4. The unit used to measure mass defect in nuclear chemistry is typically atomic mass units (amu) or MeV/c².
5. Mass defect helps explain why the actual mass of a nucleus is always less than the sum of its constituent nucleons.

Review Questions

• What causes mass defect in an atomic nucleus?
• How can you calculate binding energy from mass defect?
• Why does a larger mass defect indicate greater nuclear stability?

Related terms

Binding Energy: The energy required to disassemble a nucleus into its component protons and neutrons.

Atomic Mass Unit (amu): A unit of mass used to express atomic and molecular weights, equivalent to one twelfth of the mass of an unbound carbon-12 atom.

Nuclear Stability: A concept that describes how likely a nucleus will remain intact without undergoing radioactive decay.